Add sidebar and search box layout

Introduce a `sidebarContent` field to the `model` and update the `View`
function to render a sidebar alongside the text input, creating a basic
two-pane layout.

main.go

@@ -13,6 +13,7 @@ type model struct {
 	textInput      textinput.Model
 	width          int
 	height         int
+	sidebarContent string
 }
 
 func initialModel() model {
@@ -24,6 +25,7 @@ func initialModel() model {
 	ti.Focus()
 	return model{
 		textInput:      ti,
+		sidebarContent: "Library\n\nPlaylist 1\nPlaylist 2\nFavorites",
 	}
 }
 
@@ -51,12 +53,22 @@ func (m model) View() string {
 	if m.width == 0 {
 		return "loading..."
 	}
+
+	// Create search box
+	searchBox := lipgloss.NewStyle().BorderStyle(lipgloss.ThickBorder()).Padding(0, 1).Render(m.textInput.View())
+
+	// Create sidebar
+	sidebar := lipgloss.NewStyle().BorderStyle(lipgloss.NormalBorder()).Padding(1, 2).Render(m.sidebarContent)
+
+	// Combine search and sidebar vertically
+	content := lipgloss.JoinVertical(lipgloss.Left, searchBox, "\n", sidebar)
+
 	return lipgloss.Place(
 		m.width,
 		m.height,
 		lipgloss.Center,
-		0,
-		lipgloss.NewStyle().BorderStyle(lipgloss.ThickBorder()).Padding(0, 1).Render(m.textInput.View()),
+		lipgloss.Center,
+		content,
 	)
 }